Circuit-interrupter.



H. E, STUART. CRCUT INTERRUPTER. AIPMGANON FILED 1113.6, 1906.

Paw/med Jan. l?, WM.

WHNESSES ATTRNEY ,UNITED sTATns rilTENT onirica.

HABVE R STUART, OF WILKINSBURG, PENNSYLVANIA, ASSIGNOR TO WESTIIJGHOUSE ELECTRIC & MANUFACTURING COMPANY', A CORPORATION 0F PENNSYLVANIA.

CIRCUIT-INTERRUPTER.

Speciilcation of Letters Patent.

Application filed February 6, 1906. Serial No. 299,?6.

Patented Jan. 17, 1911.

To all whom 'it may concern:

B it known that I, HARvn R. S'rnan'r, a citizen of tbe United States, and a. resident of Wilkinsburg, in the county of Allegheny and State of Pennsylvania, have invented. la

new and useful Improvement in Circuit-` Interrupters, of 'which the following kis a under predetermined conditions, and which shall embody such operating mechanism that the engagement of the contact members and also the opening of the circuit maybe effected with the least possible injury to the interruptor.

lhen a circuit-breaker or similar device is designed for relatively highvoltage serv ice,.the stroke or range of movementoi" the movable contact member is necessarily conj siderable, and if it is operated by an electroframe i, which is mounted upon an insulating slab ci' base 2, a pair of stationary ,con-A .tact members 3 and 4, a movable Contact magnet, the movable core member of the magnet'is usually so arranged that the airgap is relatively large when the circuit in terrupter is open `and decreases to zero as the` interrupter closes the circuit. sign of the magnet and the energy supplied thereto must necessarily be adequate to start the movable parts from rest when the maximum air-gap exists, as the airgap decreases, the pull exerted by the magnet is very much increased,fso that the moving parts to which `the core member is att-ached are given a rapid acceleration, which tends to injure the contact members when they are brought together. moving Contact ine1nbeis, which are separated at a similar rate of acceleration, by reason of the action' oi' gravity, is sufficient to injure the interruptei' if they are brought to rest suddenly.

In order to avoid injurious shocks, a resilicnt sto has sometimes been provided, to be engage by the movable member at each end of its stroke, but these devices only partially obviate the diiiiculty.

According to my present invention, a specially advantageous means is employed 'fon so connecting the movable contact member to the coie of the actuating magnet that the mechanical leverage decreases as the moving Since the de-l Furthermore, the Weight of thecontact memberapproaches the stationary members, thereby compensatingwfor the increase in the pull exerted by the magnet and 'maintaining the` force, which vis ap lied di rectly to the movable contact mem er, sub stantially constant until the end of the stroke, when a slight increase is permitted in order to bring the contact members firmly linto engagement. The mechanical connection. between the parts is further arran ed to impede their downward movement a tei' the tripping device has operated to open the circuit. Small resilient stops may also advantageously be employed for preventing vany Islight shock which would otherwise occur.

My invention is illustrated in the accom- 4 panying drawings, in which `Fig-urel l is a'partial side elevation of a circuit interrupter constructed in accordance therewith, and Figs. 2 and 3 are detail views of parts of Ithe operating mechanism shown in Fig. l.

Referring to `the drawings, the'circuit in-V terrupter illustrated therein comprises i a member 5, an operating electro-magnet 6, a.

i tripping magnet 7 and an auxiliary switch.

llhestationary and movable contact members may beof any Well known construction,

preferably comprising arc-breaking contact members and current-carrying contact mem-` bers, and maybe arranged to operate in oil or other insulating fluid. The movable contact member 5 comprises a bridging contact 9, which engages the stationary Contact members 3 and 4 and completes electrical connection between them and is supported by an operating rod'l'() of insulating material, one end of vwhich is rigidly fixed t0 the bridging contact member 9 and the other end of which is pivotally connected. to one end or" a link il, the other end of said `link il being pivotally connected to the upper end of a link 12, thelower end ofv which is pivotally supported on the frame l by me/ans of a stationary pin shaft 13. A 'cam lli/is rotatably mounted upon a shaft 15, Whichis i parallel to the shaft i3 and is also mounted upon the frame l. The vcam 14 is connected to the link il by an angle link 16, the latter boing` pivotally connected to the link 11 at a point near the junction of the links l1 and 12. The cam 14 is actuated by a chain 17 which passes over a sheave 18 and is attached to a movable core nmember 19 of the electro-magnet 6. The sheave 18 is rotatably mounted upon 'a shaft 20 which is mounted upon the frame 1, parallel to the shafts 13 and 15.- One end of a guide link 21 is pivotally attached to a pro ection 23 of the frame 1 by means of a sha 22, and its other end is stantially the mi dle point of the4 link 11.

The cam 14.- is provided with a notch 24 which engages a sto 25 in order to limit the extent ot' its trave, in one direction, to a point that corresponds tothe closed position of the interrupter. One extremity of the chain 17 is attached to a projection 26 on ythe cam 14, whichis yrelatively'near its center of rotation,by an. adjusting screw 27 chain is'partially Wra pe and it is adapted .to engage a groove 28 in the periphery of the cam, ,which is eccentric or spiral in contour, so 'that,when the circuit interrupter is in its o en position, the about 'the cam within the groove, as s own in Figs. 2 and "3, so that the-point of tangency with the surface of the groove is at a materially greater distance from theicente'r of the cam than the point at which-it is attached to the projection 26. By this means, the pull exerted through the chain, by the electro-magnet, to rotate the cam, is first applied at a 'considcrable distance from the center of rotation,

' and, as the cam rotates and the air-gap in the operating electro-magnet decreases, the pull along the chain is a plied to the cam at a point which continual y moves toward the Acenter of the cam along the spiral oove, so that the leverage is'gradually d `The surface of the groove 28 which is engaged by the chain ma obviously be so arranged that the angu ar force tending to rotate the cam is substantially constant.

Although the point of' tangency between .thechain and the groove 28 of the cam is vrelatively close to the center of rotation when the circuit interrupter is closed, it is bers firmly into engagement.

slightly moreseparated therefrom than the pointV of tangency when the interrupter is employed The link 16 is adapted to 'engage a groove 29, as the cam rotates, and is eccentricallyV connected to the cam so that the point of connection is moved from a position substantially under the shaft 15 to one substantially over it. ln this way, a considerable movement of the link 11 and VVof the4 movable contact member 5 is effected by a relatively slight rotative movement of the ivotally attached to sub creased.

cam-at the mid position of its travel and a considerably increased movement of rotation of the cam is required for a similar motion of the movable contact member near each extremity of its travel.

With the. aforesaid arrangement, the speed of the movable contact member is gradually decreased as the lower limit of its travel is approached and, consequently, a severe shock is obviated and, by means of the cam and chain, the closing of the interruptor is also advantageously elfected.

W'hen the circuit interrupter is closed and ethe notch 21 on the cam 14 engages the stop 25; the'point of connection between the links 11 and, 1G is above and alittle to one side of 'the point of connection between the link 1G and the cam, so that the cam is given a tendency to rotate against the stop and the breaker `isfheld in this position.

A movable core member 30 of the tripping magnet 7 is pivotally connectedv to one end of a lever 31, which is fulcrumed upon a shaft'32. The opposite end of the lever 31 is adapted to engage the notch 24 on the cam 14, and when suicient energy is appliedto the winding of the tripping magnet 7, by reason of overload or other abnormal conditions, the cam 1l is rotated by the lever 31 through a slight angle which is sufficient to carry the point of connection between the link 16 and the cam a little to the other side of the point of connection between the links 11 and 16. When this relation exists, the combined weight of the moving contact member 5,the rod 10 and 'the link 11 is sutlicient rto continue the rotation of the cam in the Sallie direction until the movable Contact member reaches the limit of its travel.

The auxiliary switch 8 comprises a movable blade 33, which may engage either'of a. pair ofsimilar contact members 34 and 35 andis actuated by a bell crank arm CSG which is-fulcrumcd upon a stationary shaft 37, and one arm of which engages the blade 33 while the other arm is slotted to engage,-

by a lost motion connection, with a in 38 which projects from the cam 14. The ength of the bell crank arms and the arrangement of connections are such that the `switch blade 33' is thrownfrom engagement with the Contact member 35, when the circuit interrupter is open, into engagement with the contactjmember 34, when the interrupter is closed. 'lhis'switch may control an electrically operated indicating device which may indicate, ata distant point, the position occupied by the circuit interrupter, in a well known manner. The stationary and movable contact members, 3, 4 and 5 may preferably be oil-immersed in a tank 3Q.

I claim as m'y invention:

1. In a circuit breaker, the combination with stationary contact members, a movable movable member which is constant until the end of its movement, when it is slightly increased to bring the lnembers into engagement.

3. In a .circuit interrupter, the combination with stationary and movable Contact members and an operating electro-magnet, of means for applying a closing force to the movable member which is constant until the end of its movement, when it is slightly increased to bring the members into engagement, said means comprising a cam, connect ing links between the cam and the movable member and a chain which connects the armature of the electro-magnet and the cam together and cooperates with the cam Surface.

ln testimony whereof, l have hereunto subscribed my name this f30th day of Janua ry 1906.

HARVE R. STUART.

lVitnesSeS llowann (l. McDoNALn, Binner lfliNHs. 

